1. Field of the Invention
The present invention relates to an object recognition technology and, more particularly, to an object recognition apparatus capable of recognizing the position of an object, such as a person or an animal.
2. Description of the Related Art
There are methods for recognizing the position of an object by extracting the difference of image data themselves between two images and recognizing the presence of an object in the part where there is change (See Reference (1) in the following Related Art List, for instance). There are also other proposed techniques of image recognition with reduced amounts of calculations (See Reference (2) in the following Related Art List, for instance). In the technique of Reference (2), a polar coordinate system with the pixels of interest as its center is taken into consideration, and the neighborhood of the pixels of interest is quantized into divided regions of the polar coordinate system. In this quantization, the regions in the angular direction are set at equal intervals, and the regions in the radial direction are set at equal intervals on a logarithmic scale. Since this method treats a large number of pixels as a mass in the regions away from the pixels of interest, it is possible to reduce the amount of calculations even when the relationship with far distances is taken into consideration.
Related Art List
    (1) Japanese Patent Application Laid-Open No. Hei05-145844.    (2) Japanese Patent Application Laid-Open No. Hei09-171553.
When the difference of image data themselves between two images is used as in the technique of Reference (1), a large volume of memory is required because the image data themselves must be stored. Also, the amount of calculations tends to increase because of the necessity for a heavy processing such as the removal of noise. Also, if one feature vector is derived from the whole image as in the case of Reference (2), then the position of the object cannot be recognized.